Technical Field
The present disclosure relates to fabrication, on a semiconductor substrate, of microcircuits that carry electronic signals in the same process with those that carry optical signals.
Description of the Related Art
For many years, microelectronic integrated circuits (ICs) have been manufactured separately from photonic integrated circuits (PICs). Microelectronic ICs are typically built on silicon substrates. Photonic circuits are typically built on other substrates such as those made from III-V semiconductors, including gallium arsenide (GaAs), indium phosphide (InP), and the like, that have optical properties suitable for use in making semiconductor lasers for fiber optic communications. Thus, optoelectronic products, used for processing visible light signals such as, for example, waveguides, optical detectors, optical amplifiers and the like, historically have been made in separate factories from microelectronic products used for computation. Such products may include, for example, transistor-based memories and processors of various kinds such as microprocessors, specialized graphics processors, signal processors, and the like.
In the past, combining optical and electrical signals on the same IC chip has been done on a custom basis as opposed to a mass production basis. However, with the intertwining of digital processing and information storage with wireless communication functions, there is now considerable interest in mass-producing microcircuits that combine optical signal paths and electronic signal paths on a common substrate.